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Abstract:

A method for detecting a space-time block code is provided. The method
includes randomly selecting one initial candidate layer (xN) with
respect to a signal vector {tilde over (y)}, applying a DF algorithm to
first J number of layers (xN-1, xN-2, . . . , xN-J) with
respect to all the available candidate symbols within the initial
candidate layer (xN) to generate candidate symbols of each of the J
number of layers, re-arranging the J number of layers, selecting the
lowest layer of the re-arranged J number of layers as a new candidate
layer, performing a DF process on the other remaining layers, excluding
the new candidate layer, to generate N-dimensional candidate symbol
vectors xi, and performing a maximum likelihood detection on the
xi to detect an N-dimensional input vector {circumflex over (x)}.

Claims:

1. A method for detecting a space-time block code, the method
comprising:randomly selecting one initial candidate layer (xN) with
respect to a signal vector {tilde over (y)};applying a DF algorithm to
first J number of layers (xN-1, xN-2, . . . , xN-J) with
respect to each of all the available candidate symbols within the initial
candidate layer (xi) to generate candidate symbols of each of the J
number of layers;re-arranging the J number of layers;selecting the lowest
layer of the re-arranged J number of layers as a new candidate
layer;performing a DF process on the other remaining layers, excluding
the new candidate layer, to generate N-dimensional candidate symbol
vectors xi; andperforming a maximum likelihood detection on the
xi to detect an N-dimensional input vector {circumflex over (x)}.

2. The method of claim 1, wherein, in re-arranging the J number of layers,
a column order alignment is performed within an equivalent space-time
channel matrix H such that a layer having a minimum number α (
α = Δ min i α i , i = 1 , 2 , ,
J + 1 ) ##EQU00011## of candidate symbols, among the different number
of candidate symbols αi generated from each of the J number of
layers, is positioned at the undermost.

3. The method of claim 1, wherein the signal vector {tilde over (y)} is
obtained through the followings:obtaining an N-dimensional signal vector
y re-arranged with an equivalent space-time signal model with respect to
an N-dimensional reception vector y received by reception
antennas;performing QR-decomposition on the equivalent space time channel
matrix H into H=QR to generate a unitary matrix Q and an upper triangular
matrix R; andmultiplying a complex conjugate transposed matrix QH of
the unitary matrix Q to the left side of the signal vector y to generate
the N-dimensional signal vector {tilde over (y)}.

4. A method for detecting a space-time block code, the method
comprising:first randomly selecting p (p≧2) number of initial
candidate layers (xN-p, . . . xN-p+1) with respect to a signal
vector {tilde over (y)};applying a DF algorithm to first K number of
layers (xN-p, . . . xN-p-K+1) with respect to each of
combinations of all the available candidate symbols within the initial
candidate layers to generate candidate symbols of each of the K number of
layers;re-arranging the K number of layers;selecting the lowest p number
of layers, after performing the column order alignment, as new candidate
layers;performing a DF algorithm on the other remaining layers, excluding
the new candidate layers, to generate N-dimensional candidate symbol
vectors xi; andperforming a maximum likelihood detection on the
N-dimensional candidate symbol vectors xi to detect an N-dimensional
input vector {circumflex over (x)}.

5. The method of claim 4, wherein, in re-arranging the K number of layers,
a column order alignment is performed within an equivalent space-time
channel matrix H such that a combination of layers having a minimum
number ( β = Δ min i β i , i = 1 , 2 ,
, ( K p ) ) ##EQU00012## of candidate symbol vectors, among
the number βi of p-dimensional different candidate symbol
vectors generated from each of the combinations of the K number of
layers, is positioned at the undermost.

6. The method of claim 4, wherein the signal vector y is obtained through
the followings:obtaining an N-dimensional signal vector y re-arranged
with an equivalent space-time signal model with respect to an
N-dimensional reception vector y received by reception
antennas;performing QR-decomposition on the equivalent space time channel
matrix H into H=QR to generate a unitary matrix Q and an upper triangular
matrix R; andmultiplying a complex conjugate transposed matrix QH of
the unitary matrix Q to the left side of the signal vector y to generate
the N-dimensional signal vector {tilde over (y)}.

7. A receiver comprising:a processor randomly selecting one initial
candidate layer (xN) with respect to a signal vector {tilde over
(y)} and applying a DF algorithm to first J number of layers (xN-1,
xN-2, . . . , xN-J) with respect to all the available candidate
symbols within the initial candidate layer (xN) to generate
candidate symbols of each of the J number of layers, re-arranging the J
number of layers, selecting the lowest layer of the re-arranged J number
of layers as a new candidate layer and performing a DF process on the
other remaining layers, excluding the new candidate layer, to generate
N-dimensional candidate symbol vectors xi, and performing a maximum
likelihood detection on the candidate symbol vectors xi to detect an
N-dimensional input vector {circumflex over (x)}; anda transceiver
connected operatively to the processor.

8. A receiver comprising:a processor first randomly selecting p
(p≧2) number of initial candidate layers (xN, . . . ,
xN-p+1) with respect to a signal vector {tilde over (y)} and
applying a DF algorithm to first K number of layers (xN-p, . . . ,
xN-p-K+1) with respect to each of combinations of all the available
candidate symbols within the initial candidate layers to generate
candidate symbols of each of the K number of layers, re-arranging the K
number of layers, selecting the lowest p number of layers, after
performing the column order alignment, as new candidate layers and
performing a DF algorithm on the other remaining layers, excluding the
new candidate layers, to generate N-dimensional candidate symbol vectors
xi, and performing a maximum likelihood detection on the
N-dimensional candidate symbol vectors xi to detect an N-dimensional
input vector {circumflex over (x)}; anda transceiver connected
operatively to the processor.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This application claims the benefit of priority of Korean Patent
application No. 10-2009-0087731 filed on Sep. 16, 2009, all of which are
incorporated by reference in their entirety herein.

BACKGROUND OF THE INVENTION

[0002]1. Field of the Invention

[0003]The present invention relates to wireless communication and, more
particularly, to a method and apparatus for detecting space-time block
codes.

[0004]2. Related Art

[0005]Schemes using a plurality of transmission/reception antennas include
a spatial multiplexing scheme and a space-time coding scheme. The spatial
multiplexing scheme such as a vertical bell laboratory space-time
(V-BLAST) and the like is a scheme of simultaneously transmitting
independent data signals through different transmission antennas. A
receiver of a V-BLAST system employs detection schemes using QR
decomposition of an equivalent space-time channel matrix, and a DF
(Decision Feedback) algorithm, an ML (Maximum Likelihood)/DF algorithm
obtained by combining ML and DF algorithms, a PD (Parallel Detection)
algorithm, p-PD algorithm, and the like, are representative detection
schemes. Korean Patent Registration No. 10-0659281 may be referred to in
relation to definitions, content, and the like, of the detection schemes
including the p-PD algorithm. The DF algorithm based on interference
nulling and interference cancellation is very simple but causes a severe
performance degradation due to error propagation.

[0006]In the ML/DF algorithm, first some transmission layers are detected
by using the ML algorithm and the other remaining layers are detected by
using the DF algorithm. Thus, reliability of data symbols used in the
interference cancellation process can be improved.

[0007]In the PD algorithm, one layer called a candidate layer is first
selected and the DF algorithm is applied to the other remaining layers
with respect to each of candidate symbols of the candidate layer, thereby
improving performance compared with the DF algorithm. A candidate symbol
vector that minimizes Euclidean distance between candidate symbol vectors
and reception vectors obtained from the process is selected to thus make
a final decision.

[0008]The p-PD algorithm, an extended PD algorithm, is selecting two or
more candidate layers. The PD algorithm provides performance close to
that of the ML algorithm while having a rational detection complexity
over up to four transmission antennas. However, the PD algorithm shows a
severe performance degradation with an increased number of antennas.
Thus, in order to maintain the ML performance, the p-PD scheme using two
or more candidate layers is required. However, the use of more than two
candidate layers results in a considerable increase in the detection
complexity.

[0009]Meanwhile, the space-time coding scheme is a method of applying
coding to a time axis and a space axis in order to obtain both spatial
diversity and coding gain. Space-time block codes (STBCs) having
orthogonal characteristics based on an orthogonal design theory have been
proposed as a scheme for obtaining an optimum transmission antenna
diversity gain. These orthogonal STBCs (O-STBCs) have a maximum diversity
order and have an advantage in that it can detect a maximum likelihood
even by simply performing linear processing at a reception end. In case
of an STBC without having such a special structure as orthogonality, its
complexity of maximum likelihood detection increases at the ratio of
arithmetical (geometrical) progression over a modulation order Q and the
number N of transmission antennas.

[0010]Recently, there has been an attempt to apply the DF algorithm to an
STBC detection, which, however, involves a severe performance degradation
compared with the ML detection. In order to obtain performance close to
that of the ML algorithm, a sphere decoding (SD) scheme has been applied
to the STBC detection. Besides, the SD algorithm, the V-BLAST detection
algorithms such as the PD and p-PD algorithms can be also applicable to
an STBC system having an equivalent space-time channel matrix. The PD
algorithm causes a slight performance loss compared with the ML
detection, whereas the p-PD algorithm provides the substantially same
performance as that of the ML detection. However, although the detection
complexity of the PD and p-PD algorithms is significantly low compared
with the ML detection, it is still too high to be implemented over a
large modulation order.

SUMMARY OF THE INVENTION

[0011]Therefore, an object of the present invention is to provide a
quasi-optimum detection method and apparatus capable of fundamentally
reducing a detection complexity in a receiver of a general space-time
block code (STBC) system. In an aspect, a method for detecting a
space-time block code includes randomly selecting one initial candidate
layer (xN) with respect to a signal vector y, applying a DF
algorithm to first J number of layers (xN-1, xN-2, . . . ,
xN-J) with respect to all the available candidate symbols within the
initial candidate layer (xN) to generate candidate symbols of each
of the J number of layers, re-arranging the J number of layers, selecting
the lowest layer of the re-arranged J number of layers as a new candidate
layer, performing a DF process on the other remaining layers, excluding
the new candidate layer, to generate N-dimensional candidate symbol
vectors xi, and performing a maximum likelihood detection on the
xi to detect an N-dimensional input vector {circumflex over (x)}.

[0012]In re-arranging the J number of layers, a column order alignment may
be performed within an equivalent space-time channel matrix H such that a
layer having a minimum number

α ( α = Δ min i α i , i = 1
, 2 , , J + 1 ) ##EQU00001##

of candidate symbols, among the different number of candidate symbols
αi generated from each of the J number of layers, is
positioned at the undermost.

[0013]The signal vector {tilde over (y)} may be obtained through obtaining
an N-dimensional signal vector y re-arranged with an equivalent
space-time signal model with respect to an N-dimensional reception vector
y received by reception antennas, performing QR-decomposition on the
equivalent space time channel matrix H into H=QR to generate a unitary
matrix Q and an upper triangular matrix R, and multiplying a complex
conjugate transposed matrix QH of the unitary matrix Q to the left
side of the signal vector y to generate the N-dimensional signal vector
{tilde over (y)}.

[0014]In another aspect, a method for detecting a space-time block code
includes first randomly selecting p (p≧2) number of initial
candidate layers (xN, . . . xN-p+1) with respect to a signal
vector {tilde over (y)}, applying a DF algorithm to first K number of
layers (xN-p, . . . xN-p-K+1) with respect to each of
combinations of all the available candidate symbols within the initial
candidate layers to generate candidate symbols of each of the K number of
layers, re-arranging the K number of layers, selecting the lowest p
number of layers, after performing the column order alignment, as new
candidate layers, performing a DF algorithm on the other remaining
layers, excluding the new candidate layers, to generate N-dimensional
candidate symbol vectors xi, and performing a maximum likelihood
detection on the N-dimensional candidate symbol vectors xi to detect
an N-dimensional input vector {circumflex over (X)}.

[0015]In re-arranging the K number of layers, a column order alignment may
be performed within an equivalent space-time channel matrix H such that a
combination of layers having a minimum number

β ( β = Δ min i β i , i = 1 ,
2 , , ( K p ) ) ##EQU00002##

of candidate symbol vectors, among the number βi; of
p-dimensional different candidate symbol vectors generated from each of
the combinations of the K number of layers, is positioned at the
undermost.

[0016]The signal vector {tilde over (y)} is obtained through obtaining an
N-dimensional signal vector y re-arranged with an equivalent space-time
signal model with respect to an N-dimensional reception vector y received
by reception antennas, performing QR-decomposition on the equivalent
space time channel matrix H into H=QR to generate a unitary matrix Q and
an upper triangular matrix R, and multiplying a complex conjugate
transposed matrix QH of the unitary matrix Q to the left side of the
signal vector y to generate the N-dimensional signal vector {tilde over
(y)}.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a flow chart illustrating the process of a detection
method according to an exemplary embodiment of the present invention.

[0021]FIG. 5 is a schematic block diagram of a receiver implementing an
exemplary embodiment of the present invention.

[0022]FIG. 6 is a graph showing average symbol error rates (SERs) of
respective schemes obtained by experimentation by using A-ST-CR (Alamouti
Space-Time Constellation-Rotating) under the Rayleigh fading channel.

[0023]FIG. 7 is a graph showing average symbol error rates (SERs) of
respective schemes obtained by experimentation by using ST-CR (Space-Time
Constellation-Rotating) under the Rayleigh fading channel.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0024]Exemplary embodiments of the present invention will now be described
in detail with reference to the accompanying drawings.

[0025]A method for detecting a space-time block code (STBC) can be
applicable to a wireless communication system including N number of
transmission antennas and M number of reception antennas. Here, a system
using a single reception antenna will be described as an example for the
sake of brevity, but the present invention is not meant to be limited
thereto.

[0026]FIG. 1 is a flow chart illustrating the process of a detection
method according to an exemplary embodiment of the present invention.

[0027]As shown in FIG. 1, a detection method according to an exemplary
embodiment of the present invention includes outputting N-dimensional
signal vector y re-arranged with an equivalent space-time signal model
with respect to N-dimensional reception vector y received by a reception
antenna (S20), QR-decomposing an equivalent space-time channel matrix H
corresponding to the equivalent space-time signal mode to generate a
unitary matrix Q and an upper triangular matrix R (S30), multiplying a
complex conjugate transposed matrix QH of the unitary matrix Q to
the left side of the signal vector y to generate an N-dimensional signal
vector {tilde over (y)} (S40), detecting an N-dimensional input vector
{circumflex over (x)} with respect to the signal vector {tilde over (y)}
(S50).

[0028]In a general STBC, an input column vector xT=[x1, . . .
xN] having a length N is inputted to a space-time-encoder to
generate N×N codeword matrix G(x)={gt,n}. Here, the codeword
symbol gt,n, is transmitted to nth transmission antenna at tth time
interval.

[0029]It is assumed that a channel between a transmission antenna and a
reception antenna is an independent Rayleigh fading channel. It is also
assumed that a channel is a quasi-static channel not allowing a channel
value to be changed while a single codeword matrix is transmitted
therethrough. Then, a matched filter output value yt of the
reception antenna during the tth time interval is given as represented by
Equation 1 shown below:

[0030]Here, a channel constant hnhnI+jhnQ is a
complex channel gain between the nth transmission antenna and reception
antenna, and hnI and hnQ e are i.i.d. (Independent
and identically-distributed) Gaussian random variables having an average
value of 0 and a distribution value of 0.5. In addition,
wtwtI+jwtQ indicates contribution to thermal
noise at the tth time interval, and wtI and wtQ are
i.i.d. Gaussian random variables having an average value of 0 and a
distribution value of N0/2. In order to allow entire transmission
power to be equal to that of a single antenna system for a given time,
transmission power at each transmission antenna is normalized.

[0033]The N-dimensional reception vector y can be represented by Equation
3 shown below according to the equivalent space-time signal model:

y=Hx+w [Equation 3]

[0034]Here, the N-dimensional matrix y is obtained by selecting proper
elements in y as complex conjugates.

[0035]The matrix H is an N×N equivalent space-time channel matrix
including complex linear combinations of h1, . . . , hN and
their complex conjugates, which is assumed to be as a maximum rank. w is
an N-dimensional equivalent noise vector including w1, . . . ,
wN and their complex conjugates.

[0036]On the assumption that a reception terminal completely know about
the value of the equivalent space-time channel matrix H, the reception
terminal may perform a maximum likelihood detection to select an
N-dimensional input vector {circumflex over (x)} as represented by
Equation 4 shown below:

[0040]In step S40 of generating the signal vector {tilde over (y)}, the
N-dimensional signal vector {tilde over (y)} is generated by multiplying
the complex conjugate transposed matrix QH of the unitary matrix Q
to the left side of the inputted N-dimensional signal vector y as
represented by Equation 6 shown below:

[0043]FIG. 2 is a flow chart showing sub-steps of the space-time block
code detection step (S50) of FIG. 1. As for the method for detecting an
STBC with reference to FIG. 2, when the signal vector {tilde over (y)}
generated in step S40 is inputted (S51), a first DF performing step (S52)
of generating candidate symbols in each layer by applying a DF algorithm,
a step (S54) of re-arranging layers according to values of the generated
candidate symbols, a second DF performing step (S54) of generating
candidate symbols by applying the DF algorithm again to the layers
selected according to a certain reference from the re-arranged layers to
generate candidate symbols, and a maximum likelihood determination
calculation step (S58) of detecting the N-dimensional input vector
{circumflex over (x)} are performed.

[0044]The first DF performing step (S52), the layer re-arranging step
(S54), and the second DF performing step (S56) may be performed through
an RR-PD detection method, an RR-p-PD detection method, and the like.

[0045]First, a performing method according to the RR-PD detection method
will now be described as one of methods for performing the steps proposed
by the present invention. According to the RR-PD detection method, the
first DF performing step (S52), the layer re-arranging step (S54), and
the second DF performing step (856) are performed as follows: One initial
candidate layer is randomly selected with respect to an inputted signal
vector {tilde over (y)}, and a DF algorithm is applied to first J
(1≦J≦N-1) number of layers of each of them to generate
candidate symbols in each layer (S52); the column order within the
equivalent space-time channel matrix H is changed such that a layer
having the smallest value among candidate symbols corresponding to each
of the generated layers is positioned at the undermost (S54); and after
the column order alignment, the lowest layer is selected as a new
candidate layer and a DF process is performed on the other remaining
layers to generate the N-dimensional candidate symbol vectors
xi(S56).

[0046]FIG. 3 illustrates the RR-PD detection method.

[0047]In the first DF performing step (S52) one initial candidate layer is
first randomly selected with respect to a signal vector {tilde over (y)}
and the DF algorithm is applied to first J (1≦J≦N-1) number
of layers 310 with respect to all the available Q number of candidate
symbols within the initial candidate layer (xN, 300) to generate
candidate symbols of each layer. Here, the number of different candidate
symbols generated from the ith (i=1, 2, . . . , J+1) is αi.

[0048]When the minimum number of candidate symbols, among the number of
different candidate symbols αI, is α, α can be
represented by Equation 7 shown below:

α = Δ min i α i , i = 1 , 2 ,
, J + 1 [ Equation 7 ] ##EQU00007##

[0049]In the layer re-arranging step (S54), a column order alignment
(re-arrangement) is performed within the equivalent space-time channel
matrix H such that a layer having the minimum number a of candidate
symbols is positioned at the undermost, to replace the original initial
candidate layer. After the column order alignment is performed within the
equivalent space-time channel matrix H, QR decomposition is performed on
the generated new H.sub.ordered,RR-PD. FIG. 3 illustrates a case in which
the number α2 of different candidate symbols generated from
the second layer (xN-1, 360) is the smallest.

[0050]In the second DF performing step (S56), the DF algorithm is applied
to each of the α number of candidate symbols within the new
candidate layer to generate a number of candidate vectors xi(i=1, 2,
. . . , α).

[0051]In the maximum likelihood determination calculation step (S58), a
maximum likelihood determination calculation is performed on the α
number of candidate vectors (xi) to detect the N-dimensional input
vector X.

[0052]Next, a performing method according to the RR-p-PD detection method
will now be described as another method for performing the steps proposed
by the present invention. According to the RR-p-PD detection method, the
first DF performing step (S52), the layer re-arranging step (S54), and
the second DF performing step (S56) are performed as follows: A DF
algorithm is applied to first K number of layers with respect to each of
available p-dimensional candidate symbols vectors within p number of
initial candidate layers to generate candidate symbols in each layer
(S52); the column order within the equivalent space-time channel matrix H
is changed such that a combination of p number of layers in which the
number of different candidate symbol vectors is the smallest among all
the available p number of layer combinations from the K number of layers
is positioned at the undermost (S54), and after the layer re-arrangement,
p number of lowest layers are selected as new candidate layers and the DF
algorithm is performed on the other remaining layers to generate the
N-dimensional candidate symbol vectors xi (S56).

[0053]FIG. 4 illustrates the RR-p-PD detection method.

[0054]With reference to an inputted signal vector {tilde over (y)}, first,
a first DF performing unit randomly selects p number of initial candidate
layers 400 and applies the DF algorithm to first K
(p≦K≦N-p) number of layers 410 with respect to each of
QP number of all the available candidate symbol vectors 420 within
the initial candidate layers to generate candidate symbols of each layer.
The p number of different layers may be combined from the K number of
layers to generate

( K p ) ##EQU00008##

number of combinations, and

β , ( 1 ≦ β , ≦ Q p , i = 1 , 2 ,
, ( K p ) ) ##EQU00009##

number of p-dimensional candidate symbol vectors exist with respect to
each of the layer combinations.

[0055]When the minimum number of candidate symbol vectors, among the
number (βi of p-dimensional candidate symbol vectors, is
β, β may be represented by Equation 8 shown below:

β = Δ min i β i , i = 1 , 2 , , (
K p ) [ Equation 8 ] ##EQU00010##

[0056]In the layer re-arranging step (S54), a column order alignment is
performed within the equivalent space-time channel matrix H such that the
p number of layers having the minimum number β of candidate symbol
vectors are positioned at the undermost, to replace the original initial
candidate layers. After the column order alignment is performed within
the equivalent space-time channel matrix H, QR decomposition is performed
on the generated new H.sub.ordered,RR-p-PD. FIG. 4 illustrates a case in
which the number of different candidate symbol vectors with respect to
the combination of the layers corresponding to a layer index p+1, p+2, .
. . , p+K is the smallest.

[0057]In the second DF performing step (S56), the DF algorithm is applied
to each of the β number of p-dimensional candidate symbol vectors
within the new candidate layers to generate β number of
N-dimensional candidate symbol vectors xi(i=1, 2, . . . , β).

[0058]In the maximum likelihood determination calculation step (S58), a
maximum likelihood determination calculation is performed on the β
number of candidate vectors (xi) to detect the N-dimensional input
vector {circumflex over (x)}.

[0059]FIG. 5 is a schematic block diagram of a receiver implementing an
exemplary embodiment of the present invention. The receiver 500 includes
a processor 510, a memory 520, and a transceiver 530. The transceiver 530
transmits and receives radio signals. The processor 510 may be connected
to the transceiver 530 to implement the foregoing space-time block code
detection method.

[0060]The processor 510 and/or the transceiver 530 may include an ASIC
(application-specific integrated circuit), a chip-set, a logic circuit
and/or a data processor. The memory 520 may include a ROM (read-only
memory), a RAM (random access memory), a flash memory, a memory card, a
storage medium and/or any different storage unit. When an embodiment is
implemented by software, the foregoing scheme may be implemented with
modules (processes, functions, and the like) performing the foregoing
functions. The modules may be stored in the memory 520 and executed by
the processor 510. The memory 520 may be present within or outside the
processor 510 and may be connected to the processor 510 by various known
means.

[0061]FIG. 6 is a graph showing average symbol error rates (SERs) of
respective schemes obtained by experimentation by using A-ST-CR (Alamouti
Space-Time Constellation-Rotating) under the Rayleigh fading channel. The
code A-ST-CR used in the experimentation is a space-time block code,
whose format and content may be referred to the following reference
document:

[0063]It is noted from the graph of FIG. 6 that the RR-PD scheme according
to an exemplary embodiment of the present invention exhibits the
substantially same performance as that of the existing PD scheme, and the
RR-p-PD scheme according to an exemplary embodiment of the present
invention exhibits the substantially same performance as that of the
existing p-PD scheme.

[0064]FIG. 7 is a graph showing average symbol error rates (SERs) of
respective schemes obtained by experimentation by using ST-CR (Space-Time
Constellation-Rotating) under the Rayleigh fading channel. The code ST-CR
used in the experimentation is a space-time block code, whose format and
content may be referred to the following reference document:

[0066]It is noted from the graph of FIG. 7 that the RR-PD scheme according
to an exemplary embodiment of the present invention exhibits the
substantially same performance as that of the existing PD scheme, and the
RR-p-PD scheme according to an exemplary embodiment of the present
invention exhibits the substantially same performance as that of the
existing p-PD scheme.

[0070]According to Table 1, it is noted that, in the RR-PD scheme
according to an exemplary embodiment of the present invention, a
calculation complexity reduction gain drastically increases as a
modulation order increases, compared with the existing PD scheme, and in
the RR-p-PD scheme according to an exemplary embodiment of the present
invention, a calculation complexity reduction gain drastically increases
as a modulation order increases, compared with the existing p-PD scheme.

[0071]In addition, in the RR-PD scheme and the RR-p-PD scheme according to
exemplary embodiments of the present invention, the calculation
complexity reduction gain drastically increases as the modulation order
increases, compared with the existing sphere decoding scheme.

[0072]To sum up, the method for detecting a space-time block code
according to an exemplary embodiment of the present invention exhibits a
reduction in the system complexity while having the substantially same
performance compared with the related art detection methods.

[0073]In the foregoing illustrative system, the methods are described
based on the flow chart with sequential steps or blocks, but the present
invention is not meant to be limited to the order of steps and a certain
step may be performed in a different order from the foregoing order or
may be performed at the same time as another step. Also, it could be
understood by the skilled person in the art that the steps in the flow
chart are not exclusive but include any other steps or one or more steps
in the flow chart may be deleted without affecting the scope of the
present invention.

[0074]As the present invention may be embodied in several forms without
departing from the characteristics thereof, it should also be understood
that the above-described embodiments are not limited by any of the
details of the foregoing description, unless otherwise specified, but
rather should be construed broadly within its scope as defined in the
appended claims, and therefore all changes and modifications that fall
within the metes and bounds of the claims, or equivalents of such metes
and bounds are therefore intended to be embraced by the appended claims.

Patent applications by Kyung Whoon Cheun, Pohang-Si KR

Patent applications by POSTECH ACADEMY - INDUSTRY FOUNDATION

Patent applications in class Particular pulse demodulator or detector

Patent applications in all subclasses Particular pulse demodulator or detector